采用双面潜弧焊焊接了45 mm厚的TC4钛合金, 得到了内部无缺陷的对接接头, 采用光学显微镜分析了接头的显微组织。结果表明: 焊缝为β柱状晶, 柱状晶内为α′马氏体组成的网篮组织, 先焊焊缝受后一道焊缝影响, α′马氏体呈条状, 后焊焊缝高温停留时间较短, 冷却后α′马氏体为针状; 热影响区分为部分重结晶区、过渡区、细晶区与粗晶区, 且皆为等轴晶, 但尺寸及形态不同; 部分重结晶区为等轴α、β组织; 过渡区为等轴α、针状α′马氏体和残留β晶粒组织; 细晶区则为针状α′马氏体和残留β晶粒; 粗晶区组织为网篮状α′马氏体和残留β晶粒。

The TC4 titanium alloy plates with 45 mm thickness was welded by using double-sided submerged arc welding method, and then obtained the defect-free butt joint. The microstructure of welded joint was observed by optical microscopy. The results show that the microstructure of weld seam was β columnar grains, which consisted of basket-like α′-martensite. The lath α′-martensite was formed because the effect of the later weld seam on prior weld seam. The acicular α′ martensite was formed for a short residence time for lacter weld seam at high temperature; HAZ comprised part recrystal zone, transition zone, fine grain zone and coarse grain zone, the grains in HAZ were equiaxed but with different sizes and forms. The part recrystal zone consisted of equiaxed structure of α and β, transition zone consisted of equiaxed α and acicular α′ martensite and remained β grain; fine grain zone consisted of acicular α′ martensite and remain β grain, coarse-grain zone consisted of basket-like α′ and remained β grain.